Soil sampling auger

ABSTRACT

In measuring the fluid content of soil by circulating a fluid within a borehole and measuring the amount of soil fluid it entrains, the borehole is formed by drilling-in a telescoping auger that has extendable internal conduits and is arranged to form the borehole and equip it for the fluid circulation without allowing atmospheric contamination.

8 United States Patent [1 1 Wise et a].

[ Dec, 31, 1974 1 SOIL SAMPLING AUGER [75] Inventors: Harold L, Wise; Harry H. Pearce;

Milton H. Schreider; Arley Walters, all of Houston, Tex.

[73] Assignee: Shell Oil Company, Houston, Tex.

[22] Filed: Aug. 22, 1973 211 App]. No.: 390,646

[52] US. Cl. 73/4215 R, 175/58 [51-] Int. Cl. GOln l/22 [58] Field of Search 73/4215 R, 421.5 X;

[56] References Cited UNITED STATES PATENTS Clark 73/4215 R 4/1969 Meeker 175/58 8/1972 Wise 73/4215 R Primary Examiner-S. Clement Swisher [57 ABSTRACT In measuring the fluid content of soil by circulating a fluid withina borehole and measuring the amount of soil fluid it entrains, the borehole is formed by drillingin a telescoping auger that has extendable internal conduits and is arranged to form the borehole and equip it for the fluid circulation without allowing atmospheric contamination.

7 Claims, 4 Drawing Figures PATENTED M IBM 3', 857, 289

sum 10F 2 DE Q %\m; i f A PATENTED DEC3 I I974 SHEET 2 BF 2 son. SAMPLING AUGER BACKGROUND OF THE INvENTIoN vices and techniques. U.S. Pat. No. 1,843,879 (filed Dec. 3, 1929) describes a double walled cylinderical cover for a borehole. U.S. Pat. No. 2,] 12,845 describes an aspirator for drawing gas from the bottom of a borehole. U.S. Pat. Nos. 2,266,536 and 2,284,247 relate to positioning adsorbents to collect gas. U.S. Pat. No. 2,325,057 proposes a soil core cutter and U.S. Pat. No. 2,374,227 proposes positioning a vacuum bottle to be opened to collect a sample. Various means have been proposed for avoiding contamination, or improving the yield of, soil gases, for example by: separately aspirating atmospheric gas from a zone between the surface and the zone being sampled, as described in U.S. Pat. No. 2,210,546; using down-hole inflatable packers, as in U.S. Pat. No. 2,366,351; using a packing of soil and mud over an aspirating bell, as in U.S. Pat. No. 2,479,787; or using a tapered probe to compact the soil above the zones from which gas is aspirated, as in U.S. Pat. No. 3,343,42l; etc. i

The prior systems have generally applied a vacuum and have collected and measured any fluid that was drawn in by the vacuum. The results have tended to be inconsistent, as evidenced by the numerous procedures and techniques that have been proposed for improving the sampling. The consistency of a soil sampling operation is madedifficult by the relatively low concentrations of significant fluids (such as hydrocarbons) in the air or water that is normally present in the soil.

Fluids such as hydrocarbons, carbon dioxide, and the like, that may indicate the presence of a subterranean petroleum reservoir, tend to migrate through the overlying strata to the soil near the surface of the earth. Some of the migrating fluids are adsorbed on solid components of earth formations and some are dissolved or entrained in the fluid components. The hydrocarbons (for example) that are adsorbed or en trained can be measured by obtaining and analyzing a core of the soil. But soil coring operations are generally too expensive to be economically feasible. It is much cheaper to simply open a borehole and analyze the fluids that are released. However, where the fluids in the soil are collected by reducing the pressure and sucking the fluid into a chamber or system for analysis, the possibilities of contamination and failure to obtain representative samples are significant.

U.S. Pat. No. 3,685,347, by H. L. Wise, describes a fluid-circulating process for sampling the fluid in the soil around a borehole. In that process, plugs or packers are promptly inserted in freshly drilled boreholes and are arranged to permit a clear" fluid (one that contains a known and relatively small amount of the components to be measured) to be circulated into repetitive contacts with the soil exposed by the borehole. The concentration of the soil gas components are measured when they have attained a substantially equilibrium concentration in the fluid being recirculated. Field experience has indicated that although that process avoids many of the disadvantages previously encountered, significant amounts of contamination are apt to be introduced while the borehole is open to the atmosphere prior to the insertion of the plug or packer.

SUMMARY OF THE INVENTION The present invention relates to a soil sampling process. A borehole in the soil is formed by drilling-in an auger that has teeth and flightings arranged to form a substantially cylindrical borehole 'without causing any significant regranding of soil particles. The auger rotation is stopped and the soil-laden flightings are moved away from the bottom of the borehole. One end of each of a pair of conduits is opened into fluid communication with space between the auger flightings and the borehole bottom.'Fluid containing relatively small and known amounts of the component to be measured is circulated through those conduits and the exposed portion of the borehole and a measuring device, in order to entrain and measure at least one component of the fluid in the soil around the borehole.

In the present process, the procedure for circulating a clean fluid for entraining fluid from the soil being sampled is preferably similar to the fluid-circulating procedure described in U.S. Pat. No. 3,685,345, and the disclosure of that patent is incorporated herein by reference.

The present invention provides a novel soil sampling probe. The probe contains a drill bit on the end of the cylindrical inner tube which is mounted for telescopic movement, without rotation, within a cylindrical outer tube. Auger flighting projections along the outer tube are arranged to engage and transport cuttings from the bit when the bit flightings are rotated while the bit is adjac'ent to the end of the outer tube. A pair of extendable internal fluid conduits are disposed within the tubes and are arranged to be extended from points near the upper end of the outer tube to points along a portion of the inner tube when the latter has been extended beyond the lower end of the outer tube. The fluid conduits are thus provided with means for exposing and covering their lower ends when the inner tube is respectively, extended and retracted (relative to the outertube). Those conduits are also provided with means for connection their upper ends to a means for circulating and measuring the composition of a fluid.

DESCRIPTION THE DRAWINGS FIGS. 1 and 2 show the present auger in its soilpenetrating configuration.

FIGS. 3 and 4 show the present auger in its fluidcirculating configuration.

DESCRIPTION OF THE INVENTION The present invention is, at least in part, premised on a discovery that a fluid-circulating soil sampling procedure can be conducted in a manner that avoids substantially any atmosphericdilution or contamination without significantly increasing the cost of the sampling operation and such a procdure can materially reduce the effects of various surface and near-surface contamination or noise factors that tend to create problems in interpreting the data. Examples of such noise factors include (l) diluting a borehole gas with varying amounts of clean atmosphere, (2) contaminating the borehole gas with varying amounts of polluted atmosphere, (3)

in drilling a borehole, creating enough heat to cause a thermal cracking of hydrocarbons, and (4) in drilling a borehole, regrinding soil cuttings in a manner that releases hydrocarbons from partially decayed vegetation or humus; etc. I

FIGS 1 and 2 show the present auger in a soilpenetrating configuration. A drag bit 1 is mounted on an inner tube 2 that is telescoped within an outer tube 3 so that the bit is adjacent to the lower end of the outer tube. The tubes are kept from rotating relative to each other by the key 4, on the outer tube 3, that engages the keyway 6 along the inner tube 2,'and the pin 7, on the inner tube, that engages the slot 8 on the lower end of the outer tube. The bit-cuttings-transporting auger flights 9 and 9a on, respectively, the outer tube and the bit, are preferably aligned and polished to allow the cuttings to be transported freely. Such flights preferably provide a smooth continuity between the bit and the body of the auger. The bit teeth are preferably kept sharp to reduce the amount of heat build-up during the cutting of the soil. The auger flighting is preferably extended to direct contact with the bit cuttingblades, to remove the cuttings immediately and reduce the heat generation and regrinding action.

As shown in F lGS. 3 and 4, a pair of extendable partially flexible fluid conduits 11 and 11a are mounted within the inner and outer tubes 2 and 3 with their upper ends terminating in readily-accessible quickconnect conduit connections, such as connection 12. The lower ends of-the conduits l1 and 11a are connected to ports 13 and 13a at points along the inner tube 2 that becomelocated beyond the lower end of the outer tube 3 when the bit is moved away from the outer tube. The telescoping of the inner tube within the outer tube closes (covers) the lower ends of the conduits l1 and 110 while the auger is advancing into a borehole being drilled.

in a preferred embodiment, a locking screw 14 is emplaced, as shown in FIG. 1, to extend between the inner and the outer tubes and'prevent their relative lateral motion when the auger is in the drilling mode. In addition, a telltale button (not shown) is preferably mounted along outer tube. 3 so that it responds to the position of the inner tube 2 and indicates when it has extended out, and has placed the auger in the fluidcirculating mode.

The component or components of soil fluid that is sampled (or surveyed) by the present invention can be substantially any gas or liquid adapted to be measured by a chromatographic measuring system, such as a chromatographic column connected to a flame ionization detector. Such fluids can be one or more hydrocarbons, carbon dioxide, nitrogen, oxygen, hydrogen sulfide, or the like that are. mixed with or dissolved in the gas and/or water that is present in the soil.

The sample entraining fluid that is circulated into repetitive contacts with the interior of the borehole, can be substantially any pumpable fluid that is (a) at least substantially miscible with the fluid in the soil and (b) is substantially free of the soil fluid component sampled. In general, for sampling the'concentration of either an organic or inorganic gas or vapor, air that is free of the component being measured provides a preferred sample-entraining fluid. Such clean (or uncontaminate'd) air can be tanked and utilized as shown in US.

Pat. No. 3,685,345 orxcan be pressurized by means of compressor or blowers, to displace it into the circulating and analyzing system.

What is claimed is 1. A soil sampling process comprising:

penetrating the soil being sampled by drilling-in an auger having bit teeth and cuttings-transporting flightings arranged to form a substantially cylindrical borehole while avoiding any significant soil regrinding or compacting;

terminating the auger rotation and moving at least some of the auger flights away from the bottom of the borehole without removing them from the borehole;

opening a pair of conduits into fluid communication with the space between the so-moved auger flights and borehole bottom; and

circulating fluid to flow repeatedly through the conduits, through the exposed portion of the borehole and through a measuring device, in order to entrain and measure at least one component of the fluid in the soil being sampled.

2. The process of claim 1 in which the circulated fluid is air.

3. The process of claim 2 in which measurements are made of hydrocarbon and inorganic gaseous components of the fluid in the soil being sampled.

4. A soil sampling probe comprising:

adrag bit mounted on the end of a cylindrical inner tube which is arranged for telescopic movement without rotation within a cylindrical outer tube;

auger flighting on said outer tube for transporting bit cuttings from the bit when the bit and the flightings are rotated while the bit is adjacent to the lower end of the outer tube;

a pair of extendable fluid conduits that are arranged within the inner and outer tubes to extend from a location near the upper end of the outer tube to openings through the wall of the inner tube in positions in which the openings are covered by the outer tube when the inner tube is retracted within it and are beyond the lower end of the outer tube when the inner tube is extended; and

associated with said fluid conduits, means for interconnecting their upper ends with means for circulating a fluid and analyzing its content.

5. The apparatus of claim 4 in which means for circulating clean air through said conduits and a flame ionization chromatographic means for analyzing the contents of a fluid are arranged for interconnection with said fluid conduit interconnecting means.

6. The apparatus'of claim 5 in which said inner and outer tubes contain a means for locking the inner tube within the outer tube when the bit is adjacent to the lower end of the outer. tube.

7. The apparatus of claim 6 in which said inner and outer tube also contain a means for indicating whenthe inner tube has been extended to a position uncovering the lower ends of the extendable fluid conduits. 

1. A soil sampling process comprising: penetrating the soil being sampled by drilling-in an auger having bit teeth and cuttings-transporting flightings arranged to form a substantially cylindrical borehole while avoiding any significant soil regrinding or compacting; terminating the auger rotation and moving at least some of the auger flights away from the bottom of the borehole without removing them from the borehole; opening a pair of conduits into fluid communication with the space between the so-moved auger flights and borehole bottom; and circulating fluid to flow repeatedly through the conduits, through the exposed portion of the borehole and through a measuring device, in order to entrain and measure at least one component of the fluid in the soil being sampled.
 2. The process of claim 1 in whiCh the circulated fluid is air.
 3. The process of claim 2 in which measurements are made of hydrocarbon and inorganic gaseous components of the fluid in the soil being sampled.
 4. A soil sampling probe comprising: a drag bit mounted on the end of a cylindrical inner tube which is arranged for telescopic movement without rotation within a cylindrical outer tube; auger flighting on said outer tube for transporting bit cuttings from the bit when the bit and the flightings are rotated while the bit is adjacent to the lower end of the outer tube; a pair of extendable fluid conduits that are arranged within the inner and outer tubes to extend from a location near the upper end of the outer tube to openings through the wall of the inner tube in positions in which the openings are covered by the outer tube when the inner tube is retracted within it and are beyond the lower end of the outer tube when the inner tube is extended; and associated with said fluid conduits, means for interconnecting their upper ends with means for circulating a fluid and analyzing its content.
 5. The apparatus of claim 4 in which means for circulating clean air through said conduits and a flame ionization chromatographic means for analyzing the contents of a fluid are arranged for interconnection with said fluid conduit interconnecting means.
 6. The apparatus of claim 5 in which said inner and outer tubes contain a means for locking the inner tube within the outer tube when the bit is adjacent to the lower end of the outer tube.
 7. The apparatus of claim 6 in which said inner and outer tube also contain a means for indicating when the inner tube has been extended to a position uncovering the lower ends of the extendable fluid conduits. 